Foods such as black licorice can cause black diarrhea. Photo Credit rÃÂ©glisse image by corinne matusiak from <a href=http://www.fotolia.com>Fotolia.com</a>. Black diarrhea is often the sign of blood in the digestive tract that can have multiple causes depending on where the bleeding is coming from. Locations can range from anywhere from the nose or mouth to the colon, though bleeding lower in the GI tract tends to present as blood in the stool more than as black diarrhea.
gemstone - a crystalline rock that can be cut and polished for jewelry; he had the gem set in a ring for his wife; she had jewels made of all the rarest stones. gem, stone. jewellery, jewelry - an adornment (as a bracelet or ring or necklace) made of precious metals and set with gems (or imitation gems)
Are all gems minerals? A mineral is an inorganic, naturally occurring substance with distinct chemistry and crystalline structure. Gemstones are materials that have an economic or aesthetic value. Therefore, not all gemstones are minerals. For example, amber is solidified tree resin, so it is not a mineral. Gemstones can be classified as either amorphous or crystalline. Amorphous gemstones have no orderly internal atomic structure and no naturally occurring shape. Glass, amber, and opal are examples. Crystalline gemstones are minerals; they have a definite and regular internal atomic structure. Examples include garnet, emerald, and ruby. PROCEDURE: Most students are familiar with their birth month's gemstone. Poll your students and see if you can list the months and the gems just from their answers.